1. Field of the Invention
The present invention relates to an automatically engaging and disengaging clutch and more particularly to a tooth type of clutch for connecting aligned shafts or the like.
2. Description of the Prior Art
Automatic engaging and disengaging overrunning clutches of the general type described herein are well known in the art. For example, in U.S. Pat. No. 2,500,132 an overrunning clutch disconnects the starting motor shaft from the engine drive pinion when the engine becomes self-operative but also acts to reestablish the driving connection to the drive pinion if the engine does not continue to run under its own power. The driving shaft is reconnected to the driven shaft by friction and camming means acting on an intermediate clutch member when the rotational speed of the driving shaft exceeds that of the driven shaft. While this design provides satisfactory control during normal use, it has been found to generate appreciable heat during long periods of overrun at high speeds, it does not reengage promptly when the driven shaft ceases to overrun the driving shaft and the design is complex and expensive to manufacture. This design was improved in U.S. Pat. No. 2,537,017 by incorporating springs and shoes which act on the intermediate clutch member. When the speed of the engine exceeds a predetermined maximum, the shoes move radially outward against the action of the springs. This permits the driven shaft to rotate freely thereby reducing the generation of heat. If the engine should not remain self-operative, the springs move the intermediate clutch with the driving shaft by camming means so that cranking if the engine can be resumed. While this design reduced the generation of heat, it was slow to reengage the driving shaft to the driven shaft, it was very complex and expensive to fabricate. A further improvement to overrunning clutches was described in U.S. Pat. No. 3,016,122. In this design, the intermediate clutch member of the previous two prior art designs was eliminated, centrifugally movable weights were incorporated to disengage the driving shaft from the driven shaft and a frictional retarder spring was added to permit the automatic reengagement of the clutch members when the driven shaft decelerates below the speed of the driving shaft. While this design was an improvement over the previous two prior art designs, it was, nevertheless complex and expensive to manufacture. Furthermore, its range of operation is defined by the centrifugal weights.
The present design is simpler than the prior art designs in that fewer parts are required to engage and disengage the clutch jaws when there is slight relative movement of the connected shafts.